Method of operating a purifying plant and tank for practicing said method

Abstract

A method for operating an at least approximately round reactivating tank with a vertical axis for a purifying plant, according to which the sludge-water mixture to be purified is revolved in the tank and compressed air is introduced into the mixture to supply the reactivating sludge flakes of the sludge-water mixture in the tank with oxygen whereupon the mixture in the tank is forced to carry out and to maintain for a desired time a circular flow of the mixture to be purified which flow is substantially coaxial with the vertical axis of the tank. The invention also includes a reactivating tank for purifying a sludge-water mixture therein which tank has arranged therein adjacent the outer wall thereof turbine means having the axis thereof extending parallel to a tangent to the outer wall of the tank which outer wall is at least approximately round.

What I claim is: 
     
       1. A method of operating an at least approximately round reactivating tank for a purifying plant, said tank having a vertical axis and being adapted to receive a sludge-water mixture to be purified, which includes in combination the steps of: revolving in said tank the sludge-water mixture to be purified, supplying the reactivating sludge flakes of the sludge-water mixture in the tank with oxygen independently of revolving by introducing compressed air into said mixture along radial lines from adjacent the outer circumference inwardly toward the center, and increasing the volume of air outwardly from the center toward the circumference, and forcing said mixture in said tank to carry out and to maintain for a desired time a circular flow of said mixture to be purified, said flow being substantially coaxial with said vertical axis and having a radially inwardly directed component adjacent the bottom of said tank, and deflecting upwardly by centrally positioned inclined surface means said inwardly flowing mixture from said bottom as it moves toward the axis of said tank. 
     
     
       2. A reactivating tank with substantially vertical axis for purifying a sludge-water mixture adapted to be received revolving independently in said tank, which includes in combination: a bottom, an at least approximately round outer wall at least nearly uniformly spaced from said axis and confining said bottom, and means arranged in said tank adjacent said outer wall to circulate said mixture circumferentially in said tank, to produce a radially inwardly directed component of said flow, an upwardly tapering deflecting member positioned centrally on the bottom of the tank having upwardly converging surface means to deflect the inwardly directed flow upwardly, and a plurality of compressed air ventilator means extending radially outwardly adjacent the bottom of said tank, said ventilator means including outlet means increasing in total cross section radially outwardly toward said outer wall. 
     
     
       3. A tank in combination according to claim 2, in which each of said compressed air ventilator means includes a plurality of compressed air ventilators the number of which increases with the increase in the radial distance between said ventilators and said substantially vertical tank axis. 
     
     
       4. A tank in combination according to claim 3, in which said ventilator means include at least two groups of ventilators, each of said groups comprising two ventilators of different length extending close to said outer tank wall. 
     
     
       5. A tank in combination according to claim 4, in which the number of ventilators pertaining to one and the same group of ventilators increases with increasing distance from said tank axis.